Members

Cleyton Cavallaro

Christopher Grace

David Swanson

Background

The Custom Stand Up Paddleboard project is part of Michigan Technological University's BoardSport Technologies Enterprise. It is a senior capstone project that aims to develop a cheap and open source method for manufacturing top of the line paddleboards.

Materials and Techniques

Epoxy

Epoxy was chosen as a layer of Solarez epoxy between foam and fiber. This layer will give a more resilient layer to help with adhesion. Solarez epoxy does not harden fully, but remains a tacky epoxy to help give these properties. A layer of Super Sap INF from Entropy Resins was used for the outer layer. This will provide the hard shell needed for the board, and it will help increase overall strength. Both of these epoxies are resistant to UV light as well, which in essential when developing a board to be used in intense sunlight.

Super Sap INF was used for the sample testing. After running out, entropy has stopped making Super Sap INF. Super Sap One was substituted.

Foam

The Foam will be the center of the board. It will provide the buoyancy to keep the board afloat. After reducing our possible materials down to three foams, we selected Expanded Polystyrene (EPS), Divinycell Foam (PVC cross-linked), and I-Foam. Polypropylene(PP) was also tested as we did not have all material properties on I-Foam, which is a mix of PP and EPS. By testing PP we were able to predict some of the expected properties of I-Foam. These can be seen in table 1.

EPS foam was the final selection.

Fiber

The fiber layer of the board will be just across the bottom. Because of the loading of a paddleboard, the fiber on the bottom will be in tension. This is where they will lend to most strength to the board. Putting fibers on top of the board would just add to the cost with minimal strength benefits. The three fiber choices, seen in table 1, are Carbon Fiber, E-glass heavy weight, and E-glass light weight.

The final fiber choice is carbon fiber.

Stringer

Stringers help to provide additional stiffness to the board. While all testing we done without a stringer in it, the addition of a stringer is standard and cannot harm the board.

A 1/8" balsa stringer was chosen.

Blank Manufacturing

The model for the paddleboard is larger than any current CNC machine at Michigan Tech. To solve this problem, we considered both hand shaping the board and contracting out the board. Hand shaping would save on costs but would provide a lower quality board. The contracting of the board will obviously provide an easier and higher quality board, but with a cost. We decided to contract the board out to [markofoamblanks.net Marko Foam]. The total cost was $298.97 plus $233.00 for shipping. The blank was quickly cut and shipped. While we are currently still waiting on the blanks arrival, Marko has helped significantly during the entire process. The PO is linked.

Fin

Under Research

Layup Technique

Under Research

Possible Composites

During the selection of foams and fibers, CES Edupack was used to decide upon which materials were good possibilities. The 3 foams and 3 fibers were selected based on density, strength, price, and water acceptability. By optimizing these constraints we developed the final choices for testing. The charts we used to select the materials are below.

As mentioned above, the three foam choices are EPS, I-Foam, and Divinycell. The three fiber choices are Carbon Fiber, E-glass heavy, and E-glass light. More detail on the selection of these materials and the choices made can be seen in the semester report below.

The CAD model was based off over several industry standard boards. The pointed tip will help with tracking across the water, maximizing use the material properties we are striving for. Selecting the title to this section links to the CAD model page.

3D Model

Top View

Side View

Front View

Back View

Full View

Sample Testing and Data Analysis

From each of the foam and fiber choices, 9 total composite layups can be made. The samples were made to specify the ASTM requirements discussed below.

Two ASTM tests were selected to test for the expected modes of failure in our board. Knowing that the worst failures of the board could either fail from the delamination of the fiber or from brittle fracture, we tested both of these. ASTM D2344M and ASTM D7264M were the two tests we used to test laminate strength and flexural strength, respectively. Each combination of layup was tested with at least 5 samples. This gave 45 samples for each test and 90 samples total. This was done in order to ensure a significance in the results of the testing.

After the testing was competed, the data was analyzed through MINITAB, a statistical analysis software.